Carburetor



Oct. 22, 1968 G. A. WHITE CARBURETOR Filed Dec. 30, 1965 INVENTOR. zaza/Q54, /z'f'e ATTORNEY United States Patent O Filed DecfSt), 1965, Ser. No. 517,754 l Claims. (Cl. 261-50) ABSTRACT OF DISCLOSURE A carburetor having a main fuel Iwell with a peripheral wall and an insert positioned therein and closely spaced from said wall'to provide a capillary fuel passageway adapted to maintain liquid fuel in a fuel foam suspension. Also, a vapor outlet vpassage from within said insert having mounted therein an' 1insert of porous material.

This invention relates to a carburetor main well construction and is more particularly directed to means which control the iiow of fuel vapor in the carburetor main well to assure an adequate discharge of liquid fuel `from the nozzle under all conditions of operation.

In the development of an air valve carburetor, which meters fuel past a metering rod positioned by an air oW sensing valve, engine stalling due to improper fuel delivery has been encountered at high temperatures. It has been discovered that such stalling is caused by small vapor bubbles which form around the end of the metering rod and collect in a large bubble in the fuel passage. When this bubble moves through the fuel passage to the discharge nozzle in the mixture conduit, it momentarily interr-upts ow of liquid fuel through the nozzle and causes the engine to stall.

This invention provides means to collect vapor bubbles as they move through the f-uel passage so that the discharge of liquid fuel is not interrupted. The collected bubbles are subsequently discharged into the nozzle in a continuous flow which does not interfere with the flow of liquid fuel.

This invention has been found to be additionally advantageous in preventing enginestalling under conditions requiring fuel discharge at high flow rates. It has been passage to discharge nozzle. This invention provides means to maintain the liquid fuel suspended in the fuel foam so that a uniform discharge of liquid fuel is achieved.

This invention has been found to have a further advantage in preventing engine stalling after a sudden closing of the carburetor throttle. It has been discovered that such stalling is caused by a change from a flow of fuel foam to a llow of liquid fuel and a consequent delay in lling of the main well. Upon this occurrence the ow of liquid fuel through the nozzle is momentarily insufficient. This invention provides means to overcome the delay and maintain a sufficient flow of liquid lfuel to the nozzle.

The details as well as other objects and advantages of this invention are disclosed in the following description and in the drawing in which:

FIGURE 1 is an elevational view of a carburetor shown in section to illustrate the main well; and

FIGURE 2 is a view of a portion of FIGURE 1 enlarged to show the details of the main well construction.

Referring rst to FIGURE 1, a carburetor has a mixture conduit 12 controlled by a throttle valve 14. Fuel in a fuel bowl 16 is maintained at a substantially constant level by a conventional oat mechanism 17. Fuel is delivered to mixture conduit 12 from bowl 16 through a fuel passage 18 including a main well 19 and a nozzle 20.

An air valve 22 is rotatably disposed in mixture con- "ice duit 12 upon a shaft 24 and is biased to the closed position by a spring 26. A diaphragm 28 is connected to air valve 22 through a link 30. The pressure in mixture conduit 12 upstream of air -valve 22 is sensed by the lefthand side of diaphragm 28 while the pressure in mixture conduit 12 downstream of air valve 22 is sensed on the right-hand side of diaphragm 28 through a passage 32.

In operation, as throttle valve 14 is opened, the vacuum existing therebelow is applied against the downstream side of air valve 22 and the right-hand side of diaphragm 28. Such vacuum tends to open air valve 22 which admits air to reduce the pressure differential thereacross. Diaphragm 28 and spring 26 cooperate to position air valve 22 so that the subatmospheric pressure below -air valve 22 is maintained substantially constant. The position of air valve 22 is thus indicative of the rate of air flow through mixture conduit 12 to the engine.

Air valve shaft k24 is connected throughv appropriate linkage to a shaft 34 upon which a metering rod controlling arm 36 is secured. As air valve 22 opens, arm 36 raises the metering rod 38 to increase the effective fuel discharge area of a metering orifice 40. Thus fuel flow to discharge nozzle 20 is metered in accordance with air flow through mixture conduit 12 to achieve the desired ratio in the air-fuel mixture delivered to the engine.

When the carburetor is subjected to temperatures in excess of the normal operating temperature, the fuel heats and tends to form small vapor bubbles about the end of metering rod 38. These bubbles collect in a larger bubble below orice plate 40. Periodically a large bubble -breaks off and moves upwardly through passage 18. As indicated above, if this bubble is not separated from the liquid fuel in passage 18 before it reaches discharge nozzle 20, it disrupts the ow of liquid fuel through nozzle 20 and causes the engine to stall.

A vapor separator tube 42 is concentrically positioned within main well 19 to collect the bubbles moving through passage 18. The bottom of tube 42 is spaced a short distance above the bottom of main well 19 to form an opening or gap 46 of predetermined restriction. Gap 46 prevents large bubbles of fuel vapors from escaping into main well 19. T-hese bubbles instead rise in tube 42 while liquid fuel passes through gap 46. The liquid fuel then passes upwardly through main well 19 about the outside of tube 42 and is discharged through nozzle 20.

A small passage 48 connects the top of tube 42 with discharge nozzle 20 so that the fuel vapor in separator tube 42 may be continuously discharged into nozzle 20 without interrupting the iiow of liquid fuel. A porous insert 50 of sintered bronze is positioned in the top of separator tube 42 to yrestrict the flow of fuel vapor through passage 48. Thus, a continuous ow of fuel vapor to discharge nozzle 20 is achieved, and the continuous flow of liquid fuel through discharge nozzle 20 is not disturbed. It is believed that the sintered bronze absorbs liquid fuel by capillary action and prevents vapor ilow through passage 48 when only a small amount of fuel vapor is present in tube 42. As the volume of fuel vapor collected in tube 42 increases, the liquid fuel is slowly driven out of the sintered bronze and the flow of fuel vapor through passage 48 is gradually increased. Insert 50 should be s-o formed that-vapor may be discharged through passage 48 as rapidly as vapor is formed. In addition, insert 50 should be so formed that ow through passage 48 does not exceed fuel flow through inlet 18.

Under some conditions of operation, the liquid fuel in main well 19 is suspended in a fuel foam. In such circumstances, the liquid fuel occasionally separates from' the fuel foam and drops to the bottom of main well 19, thus causing a non-uniform discharge of liquid fuel from nozzle 20. However, by properly proportioning tube 42 and main well 19, the annular passage therebetween may be made sufficiently small to prevent the liquid fuel from separating out of the fuel foam. It is believed that the slight spacing of tube 42 from the peripheral wall of main well 19 provides a capillary action preventing the liquid fuel from sinking to the bottom. Thus a uniform iiow of liquid fuel is maintained through nozzle 20.

As mentioned above, under some conditions of operation the liquid fuel is supplied in a suspension of fuel foam. Under other conditions-for example, when throttle valve 14 is closed-the liquid fuel is not in a foam' suspension and requires less volume. If throttle valve 14 is suddenly closed when main well 19 contains liquid fuel in a foam suspension, an adequate delivery of fuel through nozzle 20 is delayed until sufficient fuel is metered through orifice 40 to fill main well 19 with liquid fuel. However, this delay is overcome by the provision of tube 42. When throttle valve 14 is suddenly closed, the pressure at the lower end of tube 42 falls. The fuel vapor trapped in tube 42 by insert 50 expands, forcing liquid fuel out of the lower portion of tube 42 upwardly into main well 19 and thereby filling main well 19 with liquid fuel. Thus a sufficient ow of fuel is maintained through nozzle 20.

I claim:

1. An internal combustion engine carburetor including a mixture conduit, a fuel bowl, and a main well having an inlet opening from said fuel bowl and a discharge nozzle extending into said mixture conduit, wherein said main well has a peripheral Wall and wherein an insert is positioned within said main well, said insert having at least a portion radially spaced from said wall, said main well further having said wall and said portion closely spaced providing a capillary fuel passageway therebetween adapted to maintain liquid fuel in a fuel foam suspension and thereby continuously discharge liquid fuel from said nozzle.

2. The carburetor of claim 1 wherein said insert is concentrically positioned within said main well to provide an annular fuel passageway.

3. An internal combustion engine carburetor including a mixture conduit, a fuel bowl, and a fuel delivery system comprising a main well, a tube extending downwardly into said well to form inner and outer passages, a fuel passage extending from said fuel bowl and having an outlet opening into the lower end of said tube whereby liquid fuel and fuel vapor are discharged into said inner passage, said tube being constructed to provide Opening means connecting the lower end of said inner passage to the lower end of said outer passage whereby liquid fuel is separated from fuel vapor and discharged to said outer passage, a discharge nozzle extending from said outer passage into said mixture conduit, a vapor outlet passage extending from said inner passage to said nozzle, and an insert of porous material disposed in said vapor outlet passage to form a predetermined restriction to ow of fuel vapor'through said vapor outlet passage, said insert being proportioned to permit vapor ilow at a rate at least as great as the rate of vapor formation and at a rate less than the rate of fuel iiow through said fuel passage whereby the flow of fuel vapor may be properly mixed with the flow of liquid fuel to permit a continuous flow of liquid fuel and fuel vapor through said nozzle.

4. The carburetor of claim 3 wherein said porous material is sintered bronze.

5. An internal combustion engine carburetor comprising a mixture conduit; a fuel supply system including a. fuel bowl, a main well, a fuel delivery passage extending downwardly from said fuel bowl and upwardly to said main well, and a nozzle discharging from' said main well into said mixturel conduit; a metering system comprising an air valve rotatably disposed in said mixture conduit upstream of said nozzle, the rotative position of said air valve being determined by and being a measure of the rate of air flow through said mixture conduit, a metering orifice in the downwardly extending portion of said fuel delivery passage, a vertically disposed metering rod in said fuel bowl controlling fuel liow through said orifice and means connecting said metering rod and said air valve to withdraw said rod from said orifice and increase the effective fuel discharge area upon opening movement of said air valve; and means controlling flow of liquid fuel and fuel vapor through said main well comprising a tube concentrically positioned in said m'ain Well, said fuel delivery passage extending upwardly toward said tube, the bottom of said tube being spaced from the bottom of said main well `and forming a gap adapted to separate fuel vapor from liquid fuel, a passage through which fuel vapor may be discharged from the upper end of said tube to said nozzle, and an insert of sintered bronze closing the upper end of said tube to restrict the flow of fuel vapor, said main well having a peripheral wall closely adjacent the outer surface of said tube and providing a capillary fuel passageway adapted to maintain liquid fuel suspended in a fuel foam.

References Cited UNITED STATES PATENTS 1,913,085 6/1933 Linder et al. 261-121 2,186,480 1/ 1940 Ensign 261-34 2,418,011 3/ 1947 Carlson 261-41 2,512,085 6/1950 Boller 261-121 X 3,017,167 1/ 1962 Griffen 261-34 3,278,173 10/ 1966 Cook et al. 261-50 FOREIGN PATENTS 1,112,312 11/1955 France.

HARRY B. THORNTON, Primary Examiner.

TIM R. MILES, Assistant Examiner. 

